Current-wave transmission



Feb. 7, 1928 H. J. VENNES CURRENT WAVE TRANSIISSION' Filed m. 7. 1921 I lave/72hr. v bbm/d Van/7&5.

latentcd Feb, 7, 1925 UNITED STATES PATENT OFFICE.

HARALD J. VENNES, OF NEVJ YORK, N. Y., ASSIGNOR TO \VESTEBN ELECTRIC COM- PANY, INCORPORATED, OF NEW YGRK, N. Y., A COBPORATTON OF NEW YORK.

CURRENT-WAVE TRANSMI SSION.

Application filed December '7, 1921. Serial No. 520,895.

This invention relates to the transmission of currents of diilcrent frequencies, and more particularly to systems in which currents oi dilicrent frequencies are impressed simultaneously but independently upon the same circuit, such as, for instance, in multipleX signaling, The invention comprises asimplified circuit arrangement for associating a number of diiierent current sources with a common line, whereby currents hav ing diiie-rent characterist cs are conveyed from said sources to said line-without interierence and in an eliicientmanner and whereby there is no reaction between the line and the current sources.

Heretotore, for example, as indicated in United States Patents No. 1,313,483, August 19, 1919, of R. A. Heising, and No. 1,445,141, February 13, 1923, of B. W. Kendall it has been the practice to connect current generators of difierent frequency to a common line through an amplifier for each such generator and a selective circuit be tween each amplifier and the line. This necessitates the use of as many amplifiers as there are generators and means that each selective circuit must carry the amplified cur rent and each amplifier must provide for the losses in the selective circuit due to the amplified currents.

Accord ng to this invention one amplifier sufiices for all the generators and this results in considerable saving or amplifiers, especially in systems carrying, for example, or transmissions in each direction. Also in the system according to this invention, the selective circuits carry the generated but not the amplified currents, so that the losses incurred 'in these portions of the circuit are considerably reduced Fur her, the provision of a unilateral device between the line and the individual selective circuits in the transmitting and receiving circuits, insures against any reaction between these circuits and the line due to their reactive characteristics.

In the drawing, a carrier current telegraph system is shown, in which the separation between the transmitted and received currents is effected by the use of wave filters. A Morse line arranged for full duplex op erat-ion with the carrier terminal station is also slc'wn.

Re. Ring to the drawing, a common transnii on line 1 is connected to the line 30 by a transmitting circuit and a receiving circuit,

parts of which circuits are common to plurality of channels and parts of which are individual to this channel.

The common part of the transmitting circuit comprises the wave filter 33 and the amplifier 34. The common part of the receiving circuit comprises the wave filter 35 and the amplifier 36.

- The wave filters 33 and 35 are each adapted topass a different group of frequencies, each one passing those trequ'encles whlch are characteristic of the individual channels to which they are of the general 1,227,113, May As shown, the while filter 35 connected. These filters are type described in Patent No. 22, 1917 to G, A Campbell. filter 33 is a low pass filter, is a high pass filter. The

amplifiers 34 and 36 may be of any suitable design, but are preferably electron discharge devices of well-known construction, and will not be described in further detail.

For an individual transmitting channel an oscillator 0,, which is a wellkno'Wn design, supplies energy to a loop tuned circuit 37 through the transformer 38; the loop tuned circuit 3 men transmitti Z being connected to the comng circuit through the transformer 39.' Other individual transmitting circuits may be connected to the common tive potentials batteries 43 an to the Morse line 30 from d 44, respectively. Such impulses do not ali'ect the transmitting oscillator 0 through the Morse receiving relay 45 because of the well-known Morse duplex bridge arrangement in which the Morse line 30 is balanced by the artificial line AL. Other receiving circuits may be connected to the common receiving circuit by means of other detectors which may be connected to terminals such Morse impulses incoming over the Morse line 30 actuate relay 45 to short circuit the feed-back connection of the oscillator 0 and so control the common llne.

It is to be un' output of oscillations to the derstood. of ear-tree: that there telephone receiver.

are cooperating channels at the distant end of the common line 1. By the arrangement shown, full duplex operation can be carried on between the Morse line 30 and the corresponding Morse line at the distant station. In the above arrangement no balancing networks are required for the common transmission line 1. The filters 33 and 35 are designed to pass any desired range of frequencies and their design is independent of the reactive characteristics oi the common line 1. Since the amplifiers 3t and 36 are unilateral devices, the reactive effects of the tuned transmitting and receiving channels are effectively isolated from the-common line 1.

While the particular generators, transmitters and receivers illustrated and described are for telegraph transmission, it is obvious that the invention is adaptable generally to transmission of currents of diii er-ent frequencies for the selective operation oi any desired mechanism. For example, carrier currents, modulated in accordance with any desired kind oi signal, such as speech, may be transmitted by providing the suitable transmitters and receivers such, for instance, as a microphone transmitter and a It is obvious also that transmitting and receiving antennae may be substituted for the line.

While the invention has been illustrated and described With reference to a particular system, it is to be understood that it is not to be limited tothat specific system, either as to the circuit arrangements as a whole, or to the particular details, but only by the scope of the appended claims.

\Vhat is claimed is: i

1. In a multiplex carrier Wave transmissionsystem, a plurality of oscillators fur- 'nish ing waves of respectively difierent fre circuit, individual selective circuits coupling said oscillators to said common collecting circuit, a transmission line, a band filter directly connected to said transmiss on line,

said filter being connected between said 001- lecting circuit and said line and having a transmission range broad enough to include the frequencies furnished by all of said oscillators, and a single unilateral amplifying circuit connected between said filter and said common collecting circuit, whereby said oscillators are effectively isolated from the reactive effects of said filter and line.

2. A line tor the transmission of currents inboth. directions tliereover, a plurality of sources of currents of diiierent frequencie, a plurality of individually tun-ed transmitting circuits rectly to said sources of current, a collecting circuit directly connected to each of said tuned transmitting circuits, a, plurality oi" individually tuned receiving circuits tuned 'to frequencies different from those of the transmitting circuits, a circuit common to said tuned receiving circuits, a pair of Wave t t-l' lll 'tl- 1 thin eis connec ec in para e W1 1 eaci 0 er and directly to the transmission line, said filters being adapted respectively to transmit the transmitted and received frequencies,

and a unilateral transmitting device connected in vseries With each ,oit said filters, said transmitting devices being respectively connected to the collecting transmitting circuit and to the circuit common to the tuned receiving circuits. 1

In witness whereof, I hereunto subscribe my name this 28th day oi. November, A. D.,

HARALD J. VENNES. V

respectively connected di 

